Pope Benedict XVI (L) poses with United Nations Secretary General Ban-Ki-Moon at the U.N. headquarters in New York April 18, 2008. Credit: Reuters/Lucas Jackson

The United Nations Secretary-General has responded to Pope Benedict XVI's decision to step down from his position today. In a statement, Ban Ki-Moon's spokesperson said:

"The Secretary-General expresses his appreciation for the profound commitment of Pope Benedict to inter-faith dialogue and to addressing such global challenges as the alleviation of poverty and hunger, as well as the promotion of human rights and peace.

"He hopes that the wisdom demonstrated during his Pontificate may stand as a legacy on which to build further dialogue and tolerance."

US President Barack Obama has sent his "prayers and appreciation" to Pope Benedict XVI and said the church plays a critical role in America and the world.

He also offered his "best wishes" to those selecting the Pope's successor:

"On behalf of Americans everywhere, Michelle and I wish to extend our appreciation and prayers to His Holiness Pope Benedict XVI. Michelle and I warmly remember our meeting with the Holy Father in 2009, and I have appreciated our work together over these last four years.

"The Church plays a critical role in the United States and the world, and I wish the best to those who will soon gather to choose His Holiness Pope Benedict XVI’s successor."

The Archbishop of Westminster Vincent Nichols told ITV News he had no "inkling" the pontiff would announce his resignation and said Pope Benedict XVI would be remembered "as one of the great teaching Popes."

He added: "It is a job for life, and what he has taught us is that even this job can be laid down for the right reason."